The hint helps because the title is "It SOUNDS Easy". If you sound out the words, you might get it.

I got it as soon as I read it. The "heaven" and "gate" part gave it away. My sister used to have this tape of nursery rhymes, and one of them was "This Old Man". I must've listened to that tape at least two hundred times.

I was trying to make each pair into recognizable phrases:
gun, shoe, spree, door, hive, kicks, heaven, gate, line, den
GUMSHOE, SCREEN DOOR, HIGH KICKS, HEAVEN'S GATE, LION'S DEN. But, I couldn't find a pattern; when I start out with a wrong idea, I can't break away from it.
And it was so SIMPLE! I didn't sound out the words - so I didn't get it until I read the answer. Good one - I just had a malfunction in my brain!

Doehead, if you'll consult any rhyming dictionary, you will see that "gun" is a perfect masculine rhyme for "one." And Babe, was it not a good riddle only because YOU couldn't solve it? And if so, isn't that a rather narrow criterion for determining the worth of a puzzle?

I went down the same path as avonma so the hint didn't really help as I was already playing around with sound-alike words but in pairs - because of gun(m) shoe(shot) heaven's gate and lion's den - all wrong of course.